Hi, Let me explain what I am thinking. I am only concerned about EDF scheduling policy. The scheduler determines the order in which it should schedule tasks according to their DEADLINE. I dont want to disturb that order. If a scheduler picks up a task which is computationally intensive and lets it run then due to its thermal characteristic it may heat up processor so much that eventually a hardware DTM or a frequency scaling occurs and the system slows down as a effect. Where as if the processor would have waited a little bit (only that much due to which the task would not miss its deadline) before letting the task run, and eventually lets the other computationally non intensive tasks run (from the other scheduling classes) then may be that DTM would have not occurred and may be the system would not have slowed down. So I want to solve this problem. or at least see what are the results after implementation. I can think that the scheduler need more information about the EDF tasks about their thermal (or computational) characteristics. Initially I want to supply that information when I submit a EDF task. Thank you. On Sat, Dec 27, 2014 at 3:44 AM, Henrik Austad <henrik@austad.us> wrote:

On Fri, Dec 26, 2014 at 09:14:22PM +0530, Chanchal Paul wrote:

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Hi all,

Hi Paul,

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I am trying to implement my custom scheduling policy in rt patched linux kernel. I am working with version 3.14.25-rt22. I have successfully installed the kernel after patching with rt patch of same version.

Now the installed kernel also has SCHED_DEADLINE i.e. the EDF scheduling policy.

The problem in my hand is to introduce a parameter in the SCHED_DEADLINE policy which will further dynamically change the priority according to the supplied value while the task is submitted.

You do know that SCHED_DEADLINE does not use priorities but _deadlines_, right?

care to elaborate a bit?

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I have already simulated and tested my requirement. I am having problem with understanding the hierarchy of scheduler code.

You mean the order of the scheduling policies? If you look at the sched_class in the different classes, you'll find the following hierarchy:

stop_sched_class dl_sched_class rt_sched_class fair_sched_class idle_sched_class

So, first the scheduler sees if there's any deadline tasks, then -rt and so on.

I (we) need a bit more info about what exactly it is you're struggling with

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-- Henrik Austad